Re: Life cycle costs for FORTRAN+Ada vs. Ada

[UB.com!igor!rutabaga!rjg@uunet.uu.net (Bob Geiger)]

In article <1992Apr4.190401.22260@aero.org> jordan@aero.org (Larry M. Jordan) w
rites:

>Is it "reasonable" to:
>
>[1] Develop in FORTRAN and "migrate" to Ada?
>    o Is conversion/translation of the developed FORTRAN to Ada viable?
>    o Or is it better to have a trained Ada programmer to reimplement
>      from "language independent" algorithmic descriptions of working
>      code?

This first option of conversion from Fortran to Ada is the only
one I strongly advise against. This conversion, whether automated
or manual, is likely to yield "Adatran" (Fortran-like Ada) - with
inherently poor maintainability, understandability, portability
(and several other well-known "-bilities"). I have seen this happen
and it's not a pretty sight. Avoid it if possible.
The second will work, and seems most useful if you need to deliver
a design document that describes these algorithms. If you're just
going to use them to implement in Ada, then why waste time expressing
the algorithm in a language independent way?

>[2] Or, Require the untrained to develop in Ada from the start? 
>    o Take an initial productivity hit an train scientists in Ada?
>    o And/Or have a knowledgable Ada programmer(s), who might be
>      unfamiliar with the applications area,  work closely with
>      the scientists, monitoring what's going on to guarantee "good"
>      Ada?

I prefer the second option here. Put together the heads of the
Ada expert(s) and the scientists. I have found that a little
guidance can help speed the learning curve for Ada rookies. The
reason for this is not to help teach the nuts and bolts of the
language - anyone who knows Fortran can write with a similar
style in Ada. The trick is to grasp the new capabilities of
information hiding, abstraction, and object-orientedness (or at
least object-basedness :-) ).

Hope this helps,

Bob

===========================================================================
| Bob Geiger (rjg@rational.com)        Rational                           |
| Technical Consultant                 3320 Scott Blvd.                   |
| (408) 496-3743                       Santa Clara, CA 95054-3197         |
===========================================================================
--
===========================================================================
| Bob Geiger (rjg@rational.com)        Rational                           |
| Technical Consultant                 3320 Scott Blvd.                   |
| (408) 496-3743                       Santa Clara, CA 95054-3197         |